NEW: System steers away from Chicago, sparing Windy CIty from snowfall

Tornado system kills four in Mississippi

(CNN) -- It was a frustrating day for many holiday fliers as almost 3,000 flights were postponed due to rain and poor visibility.

Chicago, Dallas and Philadelphia all were hubs of harried travelers anxiously waiting for announcements that it was time to go. At some points, those didn't come for up to two hours.

At Reagan National Airport in Washington, traveler Gregory Simpson had to wait an extra hour for his flight to Toronto.

"If you want to see family, you gotta do what you have to do," he said, taking the weather delay in stride. "It's unfortunate that this tends to happen this time of year, but there's not a whole lot you can do about it."

One man at LaGuardia International Airport in New York took advantage of the extra time. He hit the airport shops to do some last minute gift buying.

At least one holiday flight doesn't have to worry about such annoyances. Santa's aircraft, Candy Cane One, was cleared by the FAA for gift deliveries.

There were more than 2,800 delays because of weather and other reasons for flights with U.S. points of departure and/or arrivals, according to the flight tracking website FlightAware.com. More than 380 were canceled.

White Christmas for some

There was good news for snowplow drivers in Chicago as a storm system that was forecast to bring snow ended up to the east of the city. It was also weaker than expected, the National Weather Service office in Chicago said.

The folks that clear the roads Thursday in the Rockies won't be as lucky. A storm system that is moving eastward will drop snow on the mountains and the High Plains, the NWS says. Snow totals in some areas of Idaho, Montana, Utah, South Dakota and Wyoming could be significant.

The sun should return to a broad section of the southern and central United States on Thursday.

AAA projects that 98.6 million Americans will travel 50 or more miles this holiday season, a 4% increase from last year. Those traveling by car can take advantage of plummeting gas prices -- which, averaging $2.25 nationwide, are down 69 cents a gallon from a year ago.

Storms kill four in Mississippi

People grieved Wednesday and cleared rubble in southern Mississippi, where a tornado system killed four people Tuesday night and packed an emergency room with dozens of injured.

That storm tore to pieces a mobile home in the countryside of Jones County, Mississippi, killing two people, Sheriff Alex Hodge said.

"There were other brick and mortar homes that had major damage, but we have no other injuries reported," he said. The storm also wrecked a church.

A few dozen miles to the southwest, two more people died in storms in Marion County, police said. The hospital overflowed with injured people.

"Fifty patients were seen in the ER today because of the storm," said Marion General Hospital spokeswoman Millie Swan. "We are operating on generator power. Columbia is completely out of power."

At least 6,300 households lost power and roads were cut off. Emergency operators have heard of people injured and trapped. Swan expects more injured patients to come into the hospital in coming days, once they can make it in.

State of emergency

Mississippi Gov. Phil Bryant issued a state of emergency for Marion and Jones counties.

On a highway in between the two counties, the storm damaged a children's day care center, but spared the children inside.

Unharmed, they were moved to a nearby bank building.

In Louisiana, not far from the town of Amite, authorities said a windstorm damaged 15 homes.

Civil defense sirens howl from the distance on a video posted to YouTube on Tuesday purportedly of a tornado in Mississippi that day. "See it spinning?" a woman asks another.

Something on the grainy image seems to be circling in a mass of dark gray clouds on the nearby horizon.

Tornadoes are not unusual this time of year in the Deep South, said CNN meteorologist Karen Maginnis. "Actually, this is a secondary peak for tornado activity. The first is during the spring months."